Ore crusher or grinder.



G. JOHNSTON. ORE GRUSHER 0R GRINDER. APPLICATION FILED AUG.4.-1910.

Patented May 2, 1911.

- Z'SHEETS-SHEET 1.

. e. JOHNSTON. ORE CRUSHER 0R GRINDER. APPLICATION FILED AUG. 4. 1910.

2 SHEETS-SHEET 2.

Patented May 2, 1911.

GEORGE JOHNSTON, OF CHIHUAHUA, MEXICO.

ORE CBUSHER OR GRINDER.

Specification of Letters Patent.

Patented May 2, 1911.

Application filed August 4, 1910. Serial No. 575,583.

T 0 all whom it may concern:

Be it known that I, Gnonon JOHNSTON, a subject of the King ofGreatBritain and Ireland, residing at Chihuahua, Mexico, have inventedan Ore Crusher or Grinder, of which the following is a specification.

Auriferous quartz, banket material and other hard ores or substancesafter being broken down into suitably small pieces, are commonly crushedor ground by stamps, ball mills and the like to a sufficiently finecondition to admit of further treatment thereof. Such crushing orgrinding apparatus is however of great weight and cost, is expensive totransport and erect, requires heavy and secure foundations and is, compared with its output, costly to operate.

When roller mills are used for crushing or grinding hard materials ofthe kind referred to, the rolls are usually of large and substantiallyequal diameters driven at comparatively slow speeds and arranged to formbetween their upper converging surfaces a deep hopper-like space that iskept charged with the material to be crushed and ground. With such anarrangement the material forms between the upper portions of the rolls,a comparatively deep wedge shaped mass that is subjected to lateralcompression between the rolls, whereby it tends to move upward as wellas downward and cause slip and ineflicient working, and a heavy lateralunbalanced thrust is also produced on the roll bearings which causesconsiderable wear and necessitates frequent renewal thereof. Such rollermills are moreover very heavy and expensive to operate.

Now the present invention has for its object to enable auriferousquartz, banket ma terial and other hard ores or substances (hereinafterreferred to for brevity as ore) to be crushed or ground to the desireddegree of fineness in a quicker, cheaper and more convenient manner thanheretofore usual and with apparatus that can be constructed, transportedand erected in a quicker, easier and more convenient manner than thatheretofore usual and by means of which the milling cost for each ton ofore treated, can be considerably reduced as compared with the millingmethods and means now commonly employed. For this purpose, ore iscrushed or ground by feeding it, with or without water, at acomparatively slow velocity, say of the order of several hundred feetper minute, and in a comparatively thin stream between a pair of rollsone of which is made of small diameter and the other of relatively largediameter and both of which have a high peripheral velocity of the orderof say ten thousand feet per minute and upward, so that the successiveportions of the stream of material are practically subjectedindividually to a sudden nipping or crushing action between the adjacentportions of the rolls in a manner analogous to that which would resultif pieces of hard material were fed consecutively between a rapidlyacting hammer and an anvil. In this way a large quantity of ore can beeasily, quickly and cheaply dealt with.

In apparatus suitable for carrying out the invention, it is advantageousto use two pairs of small and large diameter rolls arranged with theiraxes parallel, the two smaller rolls being arranged adjacent to eachother and between the two larger rolls so that lateral thrust on thesmaller rolls is balanced and their bearings thus relieved of unduewear. Two pairs of rolls thus arranged may constitute a milling unit.two or more such units may be mounted side by side, that is to say inparallel, upon a common base plate or support or upon separate baseplates or supports and be driven in any convenient manner from a drivingshaft common to them, suitable ore feeding means being provided forsimultaneously feeding ore between each pair of rolls.

In the accompanying illustrative drawings, Figure 1 shows in sideelevation, and Fig. 2 partly in plan and partly in horizontal sectionwith the feeding means removed, one arrangement of crushing or grmdmgapparatus according to the invention. Fig. 3 is a plan of the apparatusto a smaller scale, showing the feeding means in positlon.

In the example shown, the apparatus comprises two crushing and grindingunits each comprising a pair of rolls a, b of small diameter, say forexample twenty inches in diameter, arranged adjacent to each other andbetween a pair of rolls 0, d of large diameter, say for example sixtyinches in diameter. The rolls are fixed upon parallel shafts e mountedin bearings f fixed upon a metal base piece or support 9 built up ofangle iron or otherwise suitably constructed, each shaft 6 being commonto a pair of rolls belonging to both units and provided with a beltpulley 7L. 2' is a driving pulley fixed upon a driving shaft 74 that ismounted in bearings m on the base piece 9 and is provided with a drivingwheel or pulley n by which it can be rotated at a high speed. 0 is aloose pulley. Or the shaft 76 may be driven direct at a high speed, asby a steam turbine. The Various rolls are driven simultaneously at ahigh speed from the driving pulley 2' by an endless band 79 passingaround that pulley and the pulleys '71, in the direction shown in Fig. 1so that the rolls a, b in each unit rotate in opposite directions to oneanother and to the adjacent rolls 0 and (Z. Each roll, which ispreferably made of small width, say about eighteen inches, is made witha hard peripheral crushing or grinding surface. F or this purpose it mayconveniently be provided with a renewable sleeve of hard steel, such ashardened cast carbon steel, suitably fixed in place on the roll core orbody. The several rolls, arranged at a distance apart to produce therequired degree of fineness of the material passed between them, may runin contact with each other near their outer sides and be provided withperipheral grooves Q with a view of preventing ore fed thereto escapinglaterally outward.

The ore feeding means in the example, comprises a launder 1 throughwhich the ore is fed with water and from which itis dis tributed. intohopper-like receptacles s, 6 through the bottom of which it falls inthin streams between the adjacent pairs of rapidly rotating rolls?) (Zand a 0 respectively where it is subjected to the rapid crushing andgrinding action hereinbefore referred to. The excess of water, with anyfloat gold or other matter in suspension therein, flows onward from thereceptacles s, 25 into a common discharge launder u. The entrance toeach receptacle sis provided with a perforated distributing plate 1),through which some of the ore passes to the receptacle be low, theremainder passing on to the recep tacles t.

The rolls in each pair may have the same peripheral speed or differentperipheral I speeds.

Two or more roller mills such. as described may be used through whichthe ore is successively passed so as to reduce it to the desired degreeof 1 stages.

What I claim is 1. A crushing or grinding unit comprising two pairs ofrolls of different diameters, the rolls of each pair having theircrushing surfaces in cooperative relation to receive the material to bereduced between them with .the smaller diameter roll substaining thelateral shock of the material being reduced thereon by the largerdiameter roll, the smaller diameter rolls of the two pairs beingarranged between the larger diameter rolls and running in contact tobalance the lateral thrust thereon of the material being crushed, meansfor rotating said rolls, and means for simultaneously feeding materialbetween both pairs of rolls, substantially as described.

2. crushing or grinding unit compris- 1 ing two similar pairs of rollsof different diameters having their axes in a common plane, each pairconsisting of a positively driven smaller diameter roll and a positivelydriven larger diameter roll having their crushing surfaces incooperative relation to receive and reduce the material between them,the two smaller rolls being arranged I between the two larger rolls andrunning in contact to balance the lateral thrust thereon due to thesimultaneous reducing action of the rolls of the two pairs on thematerial therebetween, means for positively and simultaneously rotatingall of said rolls, and means for simultaneously feeding material to bothpairs -of rolls, substantially as described.

Signed at New York this 26 day of July 1910.

GEORGE JOHNSTON.

Washington, D. G.

